Electric heater



Feb. 515, `1927.

A. J. KERCHE ET AL ELECTRIC HEATER Filed Nov.19. 1924 Patented Feb. 1s, 1927.

UNITED STATES PATENT OFFICE.-

ARTHUR J'. KERCHER, 0F BERKELEY, ANl) WILLIAM WESLEY HICKS, 0F SAN FRANCISCO, CALIFORNIA.

ELECTRIC HEATER.

Application led November 19, 1924. Serial No. 750,748.

This invention relates to a heating device, and more particularly to an electrically energized heater, adapted to provide heat by radiation and convection.

In order to accommodate heaters of this type in a room, it is customary to provlde a recess in the wall, in which the heater is placed. The front of the recess is ordinarily apertured or is left open to permit the escape of convection currents of heat or of radiated heat produced by the heating element. In order to further this heat transfer, it has been proposed to -use convection types of heaters, in which columns of air pass in and around the heating elements. When properly designed, the

' walls of the recess in which the heater is accommodated do not attain a temperature that is dangerously high. This has been accomplished in the past by providing an air duct of large extent between the rear wall of the recess and the heating elements, this space being a substantially continuous air passageway for convection currents induced by the' heat imparted to the walls of thepassageway. It is one of the objects of our invention to obviate the necessity of such a passageway and yet arrange the heating element in such manner that no dangerous temperatures are reached.

It is another object of our invention to improve in general this type of electric heater.

It is still another object of our` invention to make it possible to manufacture a wall type of electric heater simply and inexpensively.

From another aspect, our. invention is not limited to the particular location of the heating elements. Those features which render the invention capable of additional uses for heating, include the provision ot' a metallic envelope for the heating elements, which being closely encompassed by this metallic envelope, serve to transfer substantially all the heat to it. In this way this envelope is caused to absorb this heat and to transmit it externally by radiation or convection. Another important feature of our invention therefore resides in the particular design of this envelope,.whereby 1t serves eiliciently to transmit the heat generated or locality.

Our invention possesses other advantageous features, some of which with the foregoing, will be set forth at length in the following description, where we shall outline in full that form of the invention which we have selected for illustration in the drawings accompanying and forming part of the present specification. Although we have shown but one embodiment of our invention in the drawings, we do not desire to be limited thereto, since the invention as defined in the claims may be embodied in other forms also.

teferring to the drawings:

Figure 1 is a front View of a complete heater embodying our invention, a part of the covering grile being broken away;

Fig. 2 is a horizontal section taken along the plane 2 2 of Fig. 1; and

Fig. 3 is a vertical sectional view of the heater illustrated in Fig. 1.

4In the present inst-ance, we show a wall 11, .in which there is a recess, said recess having a lining 12 of suitable material, such as metal. As illustrated more particularly 1n Fig. 3, this metal lining has a curved upper surface and a lower flat surface or shelf 13, upon which is located a heat absorblng and transmitting member 14. This member is shown as being of cast metal and having integra-l cast legs 15. A. grille 16 in front of the casing 12 serves as a guard for the member 14.

The member 14, which envelopes one or more heating elements 17, has a rear Hat surface 18 which is polished in order to prevent undue transmission of heat from this surface 18 toward the rear surface of the recess in wall 11. On the othervhand, the front surface of the casting l14 is provided with a series of preferably vertical grooves or ridges 19 alternating with tins or ribs 20. Due to this construction, the front surface of the member 14 is provided with a very large area, and since it is left rough, it serves efficiently to transmit heat. The front surface can of course be otherwise treated if desired to increase its heat transferring qualities.

Since the envelope 14 can transmit heat effectively in one direction only, and that toward the front, no dangerous temperature can be attained in the recess -formed by the casing 12, and at the same time, heat is eiiiciently transmitted through the grille 16 and into the room where the heating is desired.

The heating elements 17 are shown in this instance as wound on refractory hollow cores 21, each having a bottom flange22 by the aid of which it may be fastened to the bottom surface of the casting 14.- The apertures 23 which are provided in the casting 14 for the accommodation of these elements 17, are made just large enough to permit the ready insertion of these elements, and to provide only a small insulation space between the elements and the member 14. In this way an efficient heat exchan e is provided for between the elements 1 and the casting 14.

ln some instances, it is desirable to expose some of the heating wire of the elements 17 so that the glow may be visible to the occupants of the room. If such an effect is desired, part of the front of the casting 14 may be cut away; for lexample by providing the oval apertures 24, which expose a part of one side of the heating elements 17. The envelope 14 takes up substantially allof the heat produced by the elements 17,v and due to the fact that the front surface is of extensive area and is roughened, it transmits the .heat efficiently either by radiation or convection, or both into the space Where the heatingis desired. No appreciable convection currents are set up between the rear surface 18 and the recess in wall 11, and the spacing of this surface from the recess is primarily for the purpose of providing still more efficient heat insulation. Thus a directional heating effect is obtained. Of course, convection currents are' set up 1n the vertical ridges 19 along the front face of the element 14, and through the grille 16. 1n order to facilitate making the electrical connections, there is a space between the bottom of casting 14 and the horizontal shelf 13.

We claim:

1. An electric air heater comprising a heat conductive member having greater height than thickness, and an electrical heating element in close thermal contact with said member, said member having an upstanding exposed rear surface of poor heat transmitting properties and an upstanding front surface of relatively good heat transmtting properties. v

2. An electric air heater comprising a heat conductive member having greater heightthan thickness, means for supporting said member in spacedrelationship to a support wall, and an electric heating element supported by said-element and in close thermal contact with the same, said member.

having an upstanding rear surface of poor heat transmitting properties and 4an upstanding front surface of relatively good heat transmitting properties.

3. In an electric wall heater, means forming a chamber having a rear wall, a heating element in said chamber, and a metallic element disposed near to and substantially 'entirely around the heating element, the rear surface of said metallic element being spaced from the rear walland being polished to minimize the transmission of heat therefrom,and the front surface having a large area of'- good heat transmitting qualit 1n an electric heater, a metallic envelope having an aperture, and a heating element inserted in said aperture and lying closely adjacent the wall of the aperture, said envelope having an upstanding exposed polished surface on one side, and a surface of good heat transmitting quality on the other side.

5 In an electric heater, a metallic envelope having an aperture, and a heating element inserted in said aperture and lying closely adjacent the wall of the aperture, saidV envelope having an upstanding exposed flat polished surface on one side, and a rough grooved surface on the other.

6. In an electric wall heater,'means forming a chamber having a rear wall, a metallic envelope in said chamber, havingan aperture, and a heating element inserted in said vaperture and lying closely adjacent the' wall the aperture, said envelope having a polished surface spaced from the rear wall, and an opposite surface of good heat transmitting guality.

7. n an electric Wall heater, means formingr a chamber having a rear wall, a metallic envelope in said chamber, having an aperture, and a heating element inserted in said aperture and lying closely adjacent the wall of the aperture, said envelope havinga flat polished surface spaced from the rear wall, and a rough grooved surface on the opposite side'.

v 8. In an electric heater, a heat absorbing member, and a plurality of electrical heating elements encased in said member, and having exposed wires that glow when energized,

ortions of the front face of the member belng open to expose at least some of the wires, the remaining portion of the front face of the member being formed to facilitate the transmission of heat therefrom.

9. ln an electric heater, a metallic inember,.and a plurality of electrical heating elements encased in said member, and having in the metallic member, and said metallic member having a flat polished surface on one side and a rough grooved surface on the other.

10. In an electric heater, a casing, a heating ele-ment within the casing, a member in which the element is inserted, arranged to transmit the heat and closely encompassing the element, the rear surface of said member being spaced from the rear wall of the casing, and formed to minimize the transfer of heat from the member into the chamber between the said rear side and rear wall, the front surface of said member being formed to facilitate transmission of heat.

11. An electric heater comprising a rear heat deflecting wall, al metallic element in front of said wall having a polished rear surface facing said wall and a front surface formed-with grooves and fins, and heating elements inserted within sai-d metallic element.

12. An electric heater comprising a rear heat deflecting wall, a metallic element in front of said wall having a polished rear surface facing saidwall, a front wall formed with fins and grooves, apertures within said metallic element and heating elements within said apertures in close proximity to the walls thereof. l

13. An electric air heater comprising a housing having a rear wall and an open front, arelativel fiat member of `heat conductive materia forming an upstanding wall, said upstanding wall being spaced from the walls of said housing whereby providing passage for convection currents of air passing into and out of said housing and having spaced upstanding ribs on its front face, an electrical heating element supported by said 'member and in thermal contact with the same, and a surface interposed between said member and rear housing wall to minimize transmission of heat to said housing.

14'. An electric air heater comprising a housing having a rear wall and an open front, a relatively fiat member of heat conductive material forming an upstanding wall, said upstan'ding Wall being spaced from ARTHUR J. mmol-IER.l WILLIAM WESLEY HICKS. 

